Issue link: https://iconnect007.uberflip.com/i/701250
18 The PCB Magazine • July 2016 Editors note: This is Keith's first in a series of columns having to do with inspection and test— from the test lab perspective. One of the more common types of failure analysis is the investigation of something that has broken. For this column, we will be discuss- ing a broken material, or, more commonly, a fractured or cracked material. Fractographic analysis is sometimes per- ceived as a difficult analysis, given its roots in material science, but one might be surprised to learn that failure modes for this type of study are well-established and well reported and can easily be found in textbooks, reference materi- als, and even with a Google search! Given that, this column is not being written to teach a les- son in fractographic failure modes, but more so to provide some insight in performing the anal- ysis yourself, or at least give you some direction to get things started. Unlike many types of forensic analyses, a fractographic investigation most times doesn't really need any high dollar, sophisticated instru- mentation or equipment. This is true because the most pertinent information in a fracture based investigation is simply the visual exami- nation of the fracture surface itself. Now, that can be problematic in some instances, because the fractured surface can become damaged be- fore it is discovered. If a crack happens and is still connected on one end, it's possible that the opposing surfaces of the frac- ture can make contact with each other—through move- ment of the specimen while still in use or even through simple vibration—potentially damaging the surface char- acteristics that are needed to determine the failure mode at hand. This is not overly com- mon, but can happen, and as such it's worth mention- ing here. For this reason, one recommendation that can be made is…don't put the pieces back together! In line with what has been mentioned just a few sentences ago, put- ting the fractured pieces back together can accidently dam- age what you're really trying to inspect. Back to the topic of the visual examination…this tru- by Keith M. Sellers NTS-BALTIMORE Seeing is Believing in Fractographic Analysis FEATURE COLUMN: LET'S TALK TESTING Figure 1: Representative overview of fracture surface using steromicroscopy.